The Prevalence and 3-Year Incidence of Dementia in Older Black and White Community Residents

Abstract

Objective: To determine the prevalence and 3-year incidence of dementia in Blacks and Whites age 65 and older in a five-county Piedmont area of North Carolina. Design: Stratified random sample of members of the Duke Established Populations for Epidemiologic Studies of the Elderly (EPESE) (baseline n = 4,136; 55% Black; weighted n ≈ 28,000). Prevalence study members were differentially selected on the basis of score on the Short Portable Mental Status Questionnaire at the second in-person Duke EPESE wave. Incidence study members included all persons with obvious cognitive decline over a 3-year period, and a 10% sample of the remainder. Measurements: Self- and informant report on health history, functional status, and memory. Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) Neuropsychology Battery administered to all subjects, and CERAD Clinical Battery to those with impaired memory. Clinical consensus to determine presence and type of dementia. Results: Prevalence of dementia for persons ⩾68 years old was 0.070 (95% confidence interval = 0.021–0.119) for Blacks and 0.072 (0.022–0.122) for Whites. Rates for Black men (0.078, 0.001–0.155) exceeded those for Black women (0.066, 0.003–0.129), but gender rates for Whites were reversed (men: 0.044, 0.000–0.103), (women: 0.087, 0.015–0.160). Neither race nor gender differences were significant. Prevalence of dementia increased through age 84 and tapered off thereafter. Three-year incidence of dementia was 0.058 (0.026–0.090) for Blacks and 0.062 (0.027–0.097) for Whites. Neither race nor gender differences were significant. Incidence increased through age 84, but moderated thereafter for all but Black men. The proportional representation of different types of dementia varied little by race. Conclusion: Prevalence, 3-year incidence, and types of dementia are comparable in Black and White elderly in the Piedmont area of North Carolina.